As long as it's for your private collection then I personally don't see anything wrong in copying for practice. Obviously if you were to start selling copies that might be a little different! To try and move on from straight copying perhaps you could find a subject similar to a painting/illustration you have already copied and try to create your own in a similar style but adding your own touches. This should help you gradually move onto doing your own stuff from scratch.
Starr, I'm the same. If I copy a drawing it doesnt look too bad. If I go step by step by following a youtube video or a book, again it isnt too bad. But when I try to do something from memory it looks like a child's work. Although having said that I did copy a still life from a book the other day and it was all out of perspective and the rendering was terrible lol. Maybe I was rushing or having a tired day.... Thank you to the others for your suggestions. I like the idea of becoming the object you are painting, becoming one with it, I try to do that with the medium I'm using and hope for the best.lol
When I was taught figure drawing (many years ago!) my teacher taught me to use the pencil to measure proportions. I also use this technique on still life.
I hold my arm out straight in front of me with the pencil upright in my clenched fist. I then align the pencil with the top of the person/figure/object and place my thumb on the pencil at key points. Once I've noted what proportions of the pencil each part takes up, I proportion my page out similarly. It's a very rough guide but can be useful.
Hopefully that makes sense but here is a guide I found also.
Copying is good for learning. It really do help in improving your skills because when we copy an object, we have this tendency to strive for perfection... on every inch of it. training wise it is very helpful specially for eye/hand coordination. Eventually we should graduate to "drawing it as we see it". Also, it is not easy to draw from ones imagination. Most of the times when I do attempt this I usually use music to get my creative juice flowing. There will be imperfections no matter what the outcome is so just try to live with it. Is it ok to copy? yes, when you're trying to improve your skills.